Light emitting apparatus and method for producing the same

ABSTRACT

A light emitting apparatus includes: a mount substrate; a first light emitting device mounted on the mount substrate; a light transparent member, wherein a lower surface of the light transparent member is attached to an upper surface of the first light emitting device via an adhesive material, wherein the light transparent member has a plate shape and is positioned to receive incident light emitted from the first light emitting device, and wherein a first lateral surface of the light transparent member is located laterally inward of a lateral surface of the first light emitting device; and a covering member that contains a light reflective material and covers at least the lateral surface of the light transparent member.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 15/811,622, filed on Nov. 13, 2017, which is a Continuation ofU.S. patent application Ser. No. 14/688,765, filed on Apr. 16, 2015,which is a Continuation of U.S. patent application Ser. No. 12/745,250,filed on May 27, 2010, which is a PCT National Phase Entry ofPCT/JP2008/071473, filed on Nov. 26, 2008, which claims priority toJapanese Patent Application No. 2007-308688, filed on Nov. 29, 2007, thedisclosures of which are hereby incorporated by reference in theirentireties.

BACKGROUND Technical Field

The present invention relates to a light emitting apparatus thatincludes a light transparent member that allows light from a lightemitting device to pass through the light transparent member, and amethod for producing the light emitting apparatus.

Background Art

Semiconductor light emitting devices are small and highly effective inpower consumption, and emit vivid color light. In light emitting devicescomposed of a semiconductor element, there are no concerns about bulbburnout and the like. In addition, semiconductor light emitting deviceshave features such as excellent initial drive characteristics, andresistance to vibration or light ON/OFF repeats. Also, light emittingapparatuses have been developed that include a light emitting device anda wavelength conversion member and can emit light of various colors. Insuch light emitting apparatuses, the light emitting device emits sourcelight, while the wavelength conversion member can be excited by thesource light to emit light of color different from the source light.Combination of the source light and the light of converted colorprovides light emission of various colors based on additive colormixture principle. Since semiconductor light emitting devices have theseexcellent features, light emitting devices such as light emitting diodes(LEDs) and laser diodes (LDs) have been used as various types of lightsources. Particularly, in recent years, attentions are given tosemiconductor light emitting devices as replacement lighting sources forfluorescent light, and next-generation lighting with lower powerconsumption and longer life than fluorescent light. Accordingly,semiconductor light emitting devices are required to further improvelight emission output and light emission efficiency. In addition, it isdesired to provide a semiconductor light emitting device that serves asa high-luminance light source such as a car headlight and a floodlight.

One example of such semiconductor light emitting devices can be given byPatent Document 1 that discloses a light emitting apparatus 100. FIG. 10shows a cross-sectional view of the light emitting apparatus 100. Thelight emitting apparatus 100 includes an LED device 102, and a case 103that is provided with the LED device 102. The case 103 has an opening ona light outgoing side. The LED device 102 is mounted in this opening.Also, the opening of the case 103 is filled with a coating material 111containing light reflective particles 111A. The coating material 111covers the external area of the LED device 102 except a light outgoingsurface 105A.

In addition, a sheet-shaped phosphor layer 110 is arranged on theexternal surface of the filling coating material 111, and on the lightoutgoing surface 105A. The phosphor layer 110 is composed of resincontaining a phosphor such as YAG (Yttrium Aluminum Garnet), which canabsorb light emitted from the LED device 2 (blue light) and be excitedby the absorbed light to emit wavelength conversion light (yellowlight). The phosphor layer 110 is arranged to cover the entire lightoutgoing surface 105A of the LED device 102, and has a light emissionsurface 110A exposed on the light outgoing side. The primary light fromthe LED device 102 (blue light) is mixed with the secondary light(yellow light) that is converted in wavelength from a part of theprimary light. As a result, white light is obtained from the lightemission surface 110A.

Patent Document 1: Japanese Patent Laid-Open Publication No, 2007-19096

Patent Document 2: Japanese Patent Laid-Open Publication No. 2002-305328

PROBLEMS TO BE SOLVED BY THE INVENTION

However, in the case of the light emitting apparatus 100 shown in FIG.10, light enters the phosphor layer 110, and then outgoes from not onlythe light emission surface 110A (see an arrow L1 in FIG. 10) but alsofrom a side surface 104 (see an arrow L2 in FIG. 10) that extends in thethickness direction. As a result, outgoing light L1 from the lightemission surface 110A side exhibits white, while the outgoing light L2from the side surface 104 side contains an insufficient blue componentof primary light and thus exhibits yellowish white light. In otherwords, the mixture color rate of the primary light and the secondarylight varies depending on parts of the phosphor layer 110. For thisreason, there is a problem of color unevenness.

Also, in the case where a plurality of light emitting apparatuses 100are combined for equipment such as lighting so that each light emittingapparatus 100 serves as a unit light source, light components from theunit light emitting apparatus may be focused or diffused by a lightcontrol system such as a lens that serves as a means for correcting thedirection of the entire outgoing light to a desired outgoing direction.In this case, it is difficult to control the outgoing direction of atransverse light component of each unit light source, and in additionthere is a color difference between the transverse light component and afrontward light component. Accordingly, the transverse light componentis interrupted since the transverse light component is likely todeteriorate the entire light emission property of the light emittingapparatuses. This causes loss of luminous flux corresponding to thetransverse light component, and luminance reduction. In other words, inthe case of the light emitting apparatus 100, since there is colorunevenness depending on parts of the phosphor layer 110 as lightemission areas, if the light emitting apparatus 100 is used as asubordinate apparatus, it is necessary to interrupt inadequate lightcomponent. Consequently, its luminous flux and luminance may relativelydecrease. Also, even if one light emitting apparatus is used, there is aproblem similar to the above problem.

As stated above, as for light that passes through the phosphor layer 110and outgoes from the light emitting apparatus, this light is composed ofmixed color light of the primary light from the LED device 102, and thesecondary light that is converted in wavelength in the phosphor layer110. Desired color light is obtained in accordance with the mixtureratio of the primary light and the secondary light. In other words, thewavelength of emitted light depends on the amount of the wavelengthconversion members, or the filling density of the wavelength conversionmember in the phosphor layer 110. Practically, if the phosphor layer 110contains an enough amount of wavelength conversion member to convert thewavelength of the outgoing light from the light source, the thickness ofthe phosphor layer 110 cannot be negligible. Although the thickness ofthe phosphor layer depends on the particle size of the wavelengthconversion member itself, and the filling density of the wavelengthconversion member, the thickness of the phosphor layer will be four ormore times that of a semiconductor structure except its growth substrateby conservative estimates and will be twenty or more times in a normalsense. That is, light emission from the side surface in the lightemitting apparatus is visually sufficiently perceivable. Accordingly,proportional to the thickness of the phosphor layer, the colorunevenness problem becomes more noticeable. In addition to this, thermalstress of the wavelength conversion member may increase in accordancewith increase of power applied to the LED when the LED is driven at alarge amount of current. Heat generated by the wavelength conversionmember and heat stress caused by the generated heat are likely to reducelight emission properties. In particular, in the case where, in order torealize a high-luminance light source, the wavelength conversion memberand the light emitting device are arranged close to or joined to eachother, the amount of heat generated by the wavelength conversion memberwill increase. In this case, a reliability problem caused by said heatmay be noticeable. Also, if a plurality of light emitting devices areintegrated to provide high luminance, this integration will furthercomplicate the problems that arise in the aforementioned single lightemitting device. For example, luminance unevenness and color unevennesscaused by the arrangement of the light emitting devices arise in thelight emission surface. In addition, since the light emission surface isincreased, the luminance unevenness and color unevenness are likely tobe affected by the density and the uneven distribution of theaforementioned wavelength conversion member, and as a result the colorunevenness will be likely to arise. In addition, since the number of thelight emitting devices increases, heat generation will increase, andcooling paths will be complicated so that heat distributiondeteriorates.

SUMMARY

The present invention is devised to solve the above conventionalproblems. It is an object of the present invention to provide a lightemitting apparatus that is excellently resistant to high temperature andcan emit light with less color unevenness at high-luminance or can emitlight at high power, and a method for producing the light emittingapparatus.

Means for Solving Problem

To achieve the aforementioned object, a light emitting apparatusaccording to a first aspect of the present invention includes a lightemitting device, a light transparent member that receives incident lightemitted from the light emitting device, and a covering member. The lighttransparent member is formed of an inorganic material light conversionmember that has an externally exposed light emission surface and a sidesurface contiguous to the light emission surface. The covering membercontains a light reflective material, and covers at least the sidesurface of the light transparent member.

Also, in a light emitting apparatus according to a second aspect of thepresent invention, the covering member surrounds the light emittingdevice.

Also, in a light emitting apparatus according to a third aspect of thepresent invention, the light transparent member is plate-shaped, and hasa light receiving surface opposed to the light emission surface. Thelight emitting device is joined to the light receiving surface.

Also, in a light emitting apparatus according to a fourth aspect of thepresent invention, the light emitting device is mounted on a mountsubstrate in a flip-chip mounting manner.

Also, in a light emitting apparatus according to a fifth aspect of thepresent invention, the covering member covers the light emitting device.

Also, in a light emitting apparatus according to a sixth aspect of thepresent invention, the light emitting device is enclosed by the lighttransparent member in plan view from the light emission surface side.

Also, in a light emitting apparatus according to a seventh aspect of thepresent invention, a plurality of light emitting devices are opticallyconnected to one light transparent member.

Also, a light emitting apparatus according to an eighth aspect of thepresent invention includes a plurality of light emitting device, acovering member that surrounds the light emitting device, and a lighttransparent member. The light transparent member is a plate-shaped lightconversion member that is made of an inorganic material, and has anexternally exposed light emission surface, a side surface contiguous tothe light emission surface and a light receiving surface opposed to thelight emission surface. The plurality of light emitting devices arejoined to the light receiving surface of the light transparent member,and light from each of the light emitting devices is incident upon thelight receiving surface. In addition, the covering member contains alight reflective material, and covers at least the side surface of thelight transparent member.

Also, in a light emitting apparatus according to a ninth aspect of thepresent invention, each of the light emitting devices is mounted on amount substrate in a flip-chip mounting manner.

Also, in a light emitting apparatus according to a tenth aspect of thepresent invention, the covering member covers each of the light emittingdevices.

Also, in a light emitting apparatus according to an eleventh aspect ofthe present invention, each of the light emitting devices is separatedaway from the covering member by a hollow part.

Also, in a light emitting apparatus according to a twelfth aspect of thepresent invention, the covering member includes, on the light emissionsurface side of the light emitting apparatus, an externally exposedsurface substantially coplanar with the light emission surface.

Also, in a light emitting apparatus according to a thirteenth aspect ofthe present invention, the light emitting device is enclosed by thelight transparent member in plan view from the light emission surfaceside.

Also, in a light emitting apparatus according to a fourteenth aspect ofthe present invention, junction areas and a covering area are arrangedon the light receiving surface side of the light transparent member. Thelight emitting devices are joined to the junction areas, and thecovering area is covered by the covering member.

Also, in a light emitting apparatus according to a fifteenth aspect ofthe present invention, the light emitting devices are separated awayfrom each other, and a separation area is arranged on the lightreceiving surface side of the light transparent member between thejunction areas. The covering area is arranged in the separation area.

Also, in a light emitting apparatus according to a sixteenth aspect ofthe present invention, the light transparent member includes aprotrusion area that protrudes outward relative to the light emittingdevices. The covering area is located in the protrusion area of thelight receiving surface.

Also, in a light emitting apparatus according to a seventeenth aspect ofthe present invention, the covering member contains, in a transparentresin, at least one oxide containing an element selected from the groupconsisting of Ti, Zr, Nb and Al as the light reflective material.

Also, in a light emitting apparatus according to an eighteenth aspect ofthe present invention, the covering member is a porous material composedof at least one material selected from the group consisting of Al₂O₃,AlN, MgF, TiO₂, ZrO₂, Nb₂O₅, SiO₂ as the light reflective materials.

Also, in a light emitting apparatus according to a nineteenth aspect ofthe present invention, the light conversion member contains a phosphor,and can convert the wavelength of at least a part of light emitted fromthe light emitting device.

Also, in a light emitting apparatus according to a twentieth aspect ofthe present invention, the light conversion member is a sinteredmaterial of an inorganic substance and the phosphor.

Also, in a light emitting apparatus according to a twenty-first aspectof the present invention, the inorganic substance is alumina (Al₂O₃),and the phosphor is YAG (Y₃Al₅O₁₂).

Also, a light emitting device production method according to atwenty-second aspect of the present invention is a method for producinga light emitting apparatus including a light emitting device, a lighttransparent member that receives incident light emitted from the lightemitting device, and a covering member. The method includes first tothird steps. In the first step, the light emitting device is mounted ona wiring substrate so that the light emitting device and the wiringsubstrate are electrically connected to each other. In the second step,at least a part of a light outgoing side opposed to the mount side ofthe light emitting device is optically connected to the lighttransparent member. In the third step, a side surface of the lighttransparent member extending in the thickness direction is covered bythe covering member. The covering member is formed so that the externalsurface of the covering member extends along the external surface theexternal surface of said light transparent member.

Effects of the Invention

In the configuration of a light emitting apparatus according to thepresent invention, as for a light transparent member, a light emissionsurface from which light outgoes is exposed from a covering member, anda side surface contiguous to the light emission surface is covered bythe covering member. That is, substantially only the light emissionsurface serves as the light emission area of the light emittingapparatus. Since the side surface is covered by the covering member,light that travels from the light emitting device to the side surfaceside is reflected by the covering member adjacent to the side surface sothat this reflected component of light can outgoes from the lightemission surface side. As a result, it is possible to avoid that lightwith different color from the central part of the light transparentmember passes the side surface and outgoes. Consequently, it is possibleto suppress that color unevenness appears. In addition, since lighttraveling toward the side surface can be directed to outgo from thelight emission surface side, it is possible to suppress the loss of theentire luminous flux amount and to improve the luminance on the lightemission surface. Accordingly, it is possible to provide emitted lighthaving excellent directivity and luminance. As a result, emitted lightcan be easily optically controlled. Therefore, in the case where eachlight emitting apparatus is used as a unit light source, the lightemitting apparatus has high secondary usability. In addition, since heatcan be conducted to the covering member, it is possible to improve heatdissipation from the light transparent member. Therefore, it is possibleto improve the reliability of the light emitting apparatus. Furthermore,in the case of a light emitting apparatus that includes a plurality ofintegrated light emitting devices, it is possible to provide uniformluminance distribution in the plane of the light emitting apparatus.Therefore, it is possible to provide a high luminance light source withreduced color unevenness.

Also, according to a light emitting apparatus production method of thepresent invention, since after a light transparent member is positioned,a side surface of the light transparent member is covered by a coveringmember, it is possible to provide desired adjustment for a lightemission surface of the light transparent member. In addition, it ispossible to easily airtightly seal a light emitting device surrounded bythe light transparent member and the covering member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Cross-sectional view schematically showing a light emittingapparatus according to an embodiment 1.

FIG. 2 Cross-sectional view schematically showing a light emittingdevice according to the embodiment 1.

FIGS. 3A, 3B, and 3C Schematic views showing a production method of thelight emitting apparatus according to the embodiment 1.

FIG. 4 Schematic view showing a production method of the light emittingapparatus according to an embodiment 2.

FIG. 5 Schematic view showing a production method of the light emittingapparatus according to an embodiment 3.

FIG. 6 Cross-sectional view schematically showing a light emittingapparatus according to an embodiment 4.

FIG. 7 Cross-sectional view schematically showing a light emittingapparatus according to a comparative example 1.

FIG. 8 Graph showing the chromaticity distribution of the light emittingapparatuses according to the example 1 and the comparative example 1.

FIG. 9 Graph showing the relationship between the ratio of side surfacerelative to light emission surface of light transparent member, andangle.

FIG. 10 Cross-sectional view showing a conventional light emittingapparatus.

FIG. 11 Graph showing the outputs of an example 3 and a comparativeexample 2 in a thermal resistance test.

FIG. 12 Graph showing the chromaticity values of the example 3 and thecomparative example 2 in a thermal resistance test.

FIG. 13 Schematic plan view showing the periphery of the lighttransparent member of the light emitting apparatus according to theexample 3 or the comparative example 2 before the thermal resistancetest.

FIG. 14 Schematic plan view showing the periphery of the lighttransparent member of the light emitting apparatus according to thecomparative example 2 after the thermal resistance test.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description will describe embodiments according to thepresent invention with reference to the drawings. It should beappreciated, however, that the embodiments described below areillustrations of a light emitting apparatus and a production method ofthe light emitting apparatus to give a concrete form to technical ideasof the invention, and a light emitting apparatus and a production methodof the light emitting apparatus of the invention is not specificallylimited to description below. In this specification, reference numeralscorresponding to components illustrated in the embodiments are added in“Claims” and “Means for Solving Problem” to aid understanding of claims.However, it should be appreciated that the members shown in claimsattached hereto are not specifically limited to members in theembodiments. Unless otherwise specified, any dimensions, materials,shapes of the components and relative arrangements of the componentsdescribed in the embodiments are given as examples and not aslimitations.

Additionally, the sizes and the arrangement relationships of the membersin each of drawings are occasionally shown larger exaggeratingly forease of explanation. Members same as or similar to those of thisinvention are attached with the same designation and the same referencenumerals, and their description is omitted. In addition, a plurality ofstructural elements of the present invention may be configured as asingle part that serves the purpose of a plurality of elements, on theother hand, a single structural element may be configured as a pluralityof parts that serve the purpose of a single element. Also, descriptionsof some examples or embodiments may be applied to another example,embodiment or the like. Also, in this specification, the term “on”(e.g., on a layer) is not limited to the state where a layer is formedin contact with an upper surface of another layer but includes the statewhere a layer is formed above an upper surface of another layer to bespaced away from the upper surface of another layer, and the state wherea layer is formed to interposes an interposition layer between the layerand another layer. In addition, in this specification, a covering memberis occasionally referred to as a sealing member.

Embodiment 1

FIG. 1 is a cross-sectional view schematically showing a light emittingapparatus 1 according to an embodiment 1 of the present invention. Thelight emitting apparatus 1 according to the example shown in FIG. 1 isprincipally configured as follows. The light emitting apparatusprincipally includes light emitting device 10, a light transparentmember 15 that allows light emitted from the light emitting device 10 topass through, and a covering member 26 that partially covers the lighttransparent member 15. The light emitting device 10 are mounted on awiring substrate 9 by electrically conductive members 24. The lighttransparent member 15 is located on the upper side of the light emittingdevice 10, and optically connected to the light emitting device 10. Thelight transparent member 15 has a light receiving surface 15 b thatreceives light from the light emitting device 10, and a light emissionsurface 15 a that serves as a plane for emitting the received light andcomposing the external surface of the light emitting apparatus 1. Inaddition, the light transparent member 15 has side surfaces 15 c thatextend substantially perpendicular to the light emission surface 15 aand in parallel to the thickness direction.

Also, parts of the light transparent member 15 are covered by thecovering member 26. The light emission surface 15 a is exposed from thecovering member 26 to emit light outward. The covering member 26contains a light reflective material 2 capable of reflecting light. Inaddition, the covering member 26 covers at least the side surfaces 15 ccontiguous to the light emission surface 15 a of the light transparentmember 15. The covering member 26 is preferably formed so that theexposed surface of the covering area of the covering member 26 issubstantially coplanar with the plane of the light emission surface 15a. According to the aforementioned configuration, light emitted from thelight emitting device 10 travels to the light transparent member 15. Thelight emission surface 15 a serves as a window portion of the lightemitting apparatus. Thus, the light outgoes from this window portion.The window portion is arranged on the forward surface side in theoutgoing direction relative to the covering member that surrounds thelight transparent member. In other words, the covering member issubstantially coplanar with the light emission surface, or is retractedfrom the light emission surface toward the light receiving surface sothat the covering member does not interrupt light from the lightemission surface of the light transparent member.

Also, the light transparent member 15 includes a wavelength conversionmember that can convert the wavelength of at least a part of lightemitted from the light emitting device 10. That is, outgoing light fromthe light emitting device 10 is added to and mixed with the secondarylight that is produced by converting the wavelength of a part of theoutgoing light. As a result, the light emitting apparatus can emit lightwith desired wavelength. Member and structures of the light emittingapparatus 1 according to the present invention will be described below.

Light Emitting Device

Known light emitting devices, specifically semiconductor light emittingdevices can be used as the light emitting device 10. GaN groupsemiconductors are preferably used since they can emit short wavelengthlight that efficiently excites fluorescent materials. Positive andnegative electrodes of the light emitting device 10 according to theembodiment 1 are formed on the same surface side. However, the positiveand negative electrodes are not limited to this arrangement. Forexample, the positive and negative electrodes may be formed onrespective surfaces. In addition, the positive and negative electrodesare not necessarily limited to one pair. A plurality of positive ornegative electrodes may be formed.

In terms of a short wavelength range of the visible light range, a nearultraviolet range or a shorter wavelength than the near ultravioletrange, a later-discussed nitride semiconductor in the followingembodiments is preferably used as a semiconductor layer 11 in a lightemitting apparatus that combines the nitride semiconductor and thewavelength conversion member (phosphor). Also, the semiconductor layeris not limited to this. The semiconductor layer can be semiconductorssuch as ZnSe group, InGaAs group, and AlInGaP group semiconductor.

Light Emitting Device Structure

The light emitting device structure formed by the semiconductor layerpreferably includes an active layer between a first conductive type(n-type) layer and a second conductive type (p-type) layer discussedlater in terms of its output and efficiency. However, the structure isnot limited to this. Each conductive layer may partially includes aninsulating, semi-insulating, or opposite conductive type structure.Also, such a structure may be additionally provided to the first orsecond conductive type layer. Another type structure such as protectiondevice structure may be additionally provided to the first or secondconductive type layer. Also, the aforementioned substrate may serve as apart of conduction type layer of the light emitting device. In the casewhere the substrate does not compose the light emitting devicestructure, the substrate may be removed. Also, the growth substrate maybe removed after the semiconductor layers are formed, and the separatedsemiconductor device structure, i.e., the separated semiconductor layersmay be adhered onto or mounted in a flip chip mounting manner on asupport substrate such as a conductive substrate. Also, anothertransparent member and another transparent substrate may be adhered ontothe semiconductor layers. Specifically, in the case where the growthsubstrate, or the adhered member or substrate is located on the lightoutgoing side of semiconductor layers as a main surface, the growthsubstrate, or the adhered member or substrate has transparency. In thecase where the growth substrate does not have transparency, or blocks orabsorbs light, and the semiconductor layers are adhered onto such asubstrate, the substrate is located on the light reflection side of thesemiconductor layer main surface. In the case were charge is provided tothe semiconductor layers from a transparent substrate or member on thelight outgoing side, the transparent substrate or member will haveconductivity. Also, the light transparent member 15 may be used insteadof the transparent member or substrate connected to the semiconductorlayers. In addition, in the device, the semiconductor layers may beadhered or covered, and supported by a transparent member such as glassand resin. The growth substrate can be removed by grinding the growthsubstrate held on a chip mounting portion of a sub-mount or apparatus,or LLO (Laser Lift Off) for the held growth substrate, for example. Evenin the case of a transparent different type substrate, it is preferableto remove the substrate. The reason is that light outgoing efficiencyand output can be improved.

Examples of the structure of the light emitting device or semiconductorlayers 11 can be given by homo structure, hetero structure ordouble-hetero structures with MIS junction, PIN junction or PN junction.A superlattice structure can be applied to any layer. The active layer 8can have a single or multi-quantum well structure provided with thinlayer(s) for quantum effect.

As for the electrodes arranged on the semiconductor layer, it ispreferable that first conductive type (n-type) and second conductivetype (p-type) layer electrodes are located on one surface as mainsurface as discussed later and in examples. However, the electrodes arenot limited to this arrangement. The electrodes may be located on themain surfaces of semiconductor layers and be opposed to each other. Forexample, in the case of the aforementioned substrate-removed structure,one of the electrodes can be arranged on the removal side. The lightemitting device can be mounted in known manners. For example, in thecase where the device structure has the positive/negative electrodes onthe same surface side, the light emitting device can be mounted so thatthe electrode formation surface serves as the main light outgoingsurface. In terms of heat dissipation, the flip tip mounting ispreferable in that the growth substrate side opposed to the electrodeformation side serves as the main light outgoing surface as discussedlater and in examples. In addition to this, mounting methods suitablefor device structures can be used.

The light emitting devices 10 installed on the light emitting apparatus1 shown FIG. 1 are LED chips, which are nitride semiconductor devices.LED chips are mounted on the sub-mount as one of wiring substrate 9 in aflip chip mounting manner. FIG. 2 is a cross-sectional viewschematically showing the light emitting device 10. The light emittingdevice 10 shown in FIG. 2 is an exemplary light emitting device.

The structure of the light emitting device 10 is described withreference to FIG. 2. The light emitting device 10 includes nitridesemiconductor layers as the semiconductor structure 11 that arelaminated on the growth substrate 5 as one main surface side of a pairof main surfaces opposed to each other. In the semiconductor structure11, a first nitride semiconductor layer 6, the active layer 8, and asecond nitride semiconductor layer 7 are laminated in this order fromthe bottom side. Also, the first electrode 3A and the second electrode3B are electrically connected to the first nitride semiconductor layer 6and the second nitride semiconductor layer 7, respectively. Whenelectric power is supplied from an outside source via the firstelectrode 3A and the second electrode 3B, the light emitting device 10emits light from the active layer 8. The following description willdescribe a production method of a nitride semiconductor light emittingdevice as an example of the light emitting device 10.

Light Reflection Structure

The light emitting device 10 can have a light reflection structure.Specifically, the light reflection side can be one main surface (lowerside in FIG. 1) opposed to the light outgoing side of the two mainsurfaces of the semiconductor layers opposed to each other. The lightreflection structure can be arranged on this light reflection side, andin particular can be arranged inside of the semiconductor layerstructure, on the electrode, or the like.

Transparent Conductive Layer

As shown in FIG. 2, a transparent conductive layer 13 is formed on thep-type semiconductor layer 7. In addition, a conductive layer can alsobe formed substantially entirely on an exposed surface of the n-typesemiconductor layer 6. Alternatively, in the case where a reflectionstructure is arranged on the transparent conductive layer 13, theelectrode formation surface side can serves as the reflection side.Alternatively, in the case where a transparent conductive layer isexposed from a pad electrode, light can outgoes from this transparentconductive layer. Alternatively, a reflective electrode may be arrangedon the semiconductor layer structure without such a transparentconductive layer. The transparent conductive layer 13 is not limited tocover each of the n-type semiconductor layer 6 and the p-typesemiconductor layer 7, but can cover only one of the semiconductorlayers. The transparent conductive layer 13 is preferably composed ofoxide that contains at least one element selected from the groupconsisting of Zn, In, and Sn. Specifically, the transparent conductivelayer 13 is used that includes oxide of Zn, In and Sn such as ITO, ZnO,In₂O₃ and SnO₂. Preferably, ITO is used. Alternatively, the transparentconductive layer may have a light transparent structure, for example, ametal film that is configured by forming metal as Ni into a thin filmwith thickness of 3 nm, a metal film of oxide of other metal, nitride orother compound with openings as window portions. In the case where theconductive layer is formed substantially entirely on the exposed p-typesemiconductor layer 7, current can spread uniformly on the entire p-typesemiconductor layer 7. In addition, the thickness and the size of thetransparent conductive layer 13 can be designed in terms of the lightabsorption and electrical resistance/sheet resistance i.e., thetransparency and reflection structure and current spreading of thelayer. For example, the thickness of the transparent conductive layer 13can be not more than 1 μm, more specifically 10 nm to 500 nm.

Electrode

The electrode layer is formed on the semiconductor layer structure. Inthe case where the aforementioned transparent conductive layer isinterposed between the electrode layer and the semiconductor layerstructure, the electrode layer is electrically connected to thetransparent conductive layer. The electrodes are formed in contact withthe transparent conductive layers 13 suitably arranged on the p-typesemiconductor layer 7 and the n-type semiconductor layer 6 side, or onthe semiconductor structure so that the first electrode 3A and thesecond electrode 3B are configured. The electrode layers can beelectrically connected to the light emitting device 10 and the externalterminals to serve as pad electrodes. For example, the electricallyconductive members 24 such as Au bumps are arranged on the surfaces ofthe metal electrode layers so that the electrodes of the light emittingdevice are electrically connected to the external terminals opposed tothese electrodes via the electrically conductive members. Also, in thecase of FIG. 2, the metal electrode layer 3B overlaps the transparentconductive layer 13, and is electrically directly connected to thetransparent conductive layer 13. The pad electrode suitably has a knownconfiguration. For example, the electrode is formed of any one metal ofAu, Pt, Pd, Rh, Ni, W, Mo, Cr and Ti, or an alloy or a combination ofthem. An exemplary metal electrode layer can have a lamination structureof W/Pt/Au, Rh/Pt/Au, W/Pt/Au/Ni, Pt/Au or Ti/Rh in this order from thebottom surface side.

As for the electrode layers formed on the p-type nitride semiconductorlayer 7 and the n-type nitride semiconductor layer 6 side of theaforementioned nitride semiconductor light emitting device or therespective conduction type electrodes, the electrodes layers or therespective conduction type electrodes preferably have the sameconfiguration in types, layer thicknesses and layer structures ofmetals. The reason is that formation of the electrodes layers or therespective conduction type electrodes together can simplify a formationprocess of electrodes including the aforementioned transparentconductive layers as compared with separate formation. In the case ofseparate formation, the electrode on the n-type nitride semiconductorlayer side can be a W/Pt/Au electrode (for example, the layerthicknesses are 20/200/500 nm) or an additionally-Ni-laminated electrodeof W/Pt/Au/Ni, a Ti/Rh/Pt/Au electrode or the like.

Protection Film

After the metal electrode layer is formed, an insulating protection film14 can be formed substantially on the entire surface of thesemiconductor light emitting device 10 except for connection areas tothe external areas. In the case of FIG. 2, openings are formed in theprotection film 14 that covers the n-type electrode 3A part and thep-type electrode 3B part to form exposed areas for the electrodes. Theprotection film 14 can be formed of SiO₂, TiO₂, Al₂O₃, polyimide or thelike.

Also, as for the light emitting devices installed on the light emittingapparatus, although the light emission peak wavelength of outgoing lightemitted from the light emitting layer is not specifically limited,semiconductor light emitting devices can be used that have an emissionspectrum of about 240 nm to 500 nm, which corresponds to the nearultraviolet range to the visible short wavelength range, preferably of380 nm to 420 nm or of 450 nm to 470 nm.

Nitride Semiconductor Light Emitting Device

The following description will describe a nitride semiconductor lightemitting device as an example of the light emitting device 10 and aproduction method of the nitride semiconductor light emitting device.

In the light emitting device 10 of nitride semiconductor of FIG. 2, then-type semiconductor layer as the first nitride semiconductor layer 6,the light emitting layer as the active layer 8, and the p-typesemiconductor layer as the second nitride semiconductor layer 7 areepitaxially grown on the sapphire substrate as the growth substrate 5 inthis order so that the nitride semiconductor layer structure 11 isformed. Subsequently, the light emitting layer 8 and the p-typesemiconductor layer 7 are selectively partially etched and removed sothat the n-type semiconductor layer 6 is partially exposed. The n-typepad electrode as the first electrode 3A is formed on the exposed area.The p-type pad electrode as the second electrode 3B is formed on thetransparent conductive layer 13 on the same plane side as the n-typeelectrode 3A. In addition, only predetermined surface parts of then-type pad electrode 3A and the p-type pad electrode 3B are exposed, andother parts can be covered by the insulating protection film 14. Then-type pad electrode 3A may be formed on the exposed area of the n-typesemiconductor layer 6 to interpose the transparent conductive layerbetween them. When electric power is supplied from an outside source viathe first electrode 3A and the second electrode 3B, the light emittingdevice 10 emits light from the active layer 8. Light mainly outgoes fromthe upper surface side as shown by arrows in FIG. 1. That is, in thelight emitting device 10 shown in FIG. 1, the electrode formationsurface side is the mount side (lower side in FIG. 1), while other mainsurface side (upper side in FIG. 1) opposed to the electrode formationsurface side is the main light outgoing side. The following descriptionwill specifically describe constituent elements of the semiconductorlight emitting device 1.

Growth Substrate

The semiconductor layer structure 11 epitaxially grows on the growthsubstrate 5. The growth substrate 5 for nitride semiconductor can besapphire with C facet, R facet or A facet as principal surface, aninsulating substrate such as spinel (MgAl₂O₄), silicon carbide (6H, 4H,or 3C), Si, ZnS, ZnO, GaAs, diamond, an oxide substrate capable ofjoining with nitride semiconductor with lattice matching such as lithiumniobate and neodymium gallate, or a nitride semiconductor substrate suchas GaN and AlN.

Nitride Semiconductor Layer

The nitride semiconductor is formed of general formulaIn_(x)Al_(y)Ga_(1-x-y)N (0≤x, 0≤y, x+y≤1), and may be mixed with B, P,or As. The n-type semiconductor layer 6 and the p-type semiconductorlayer 7 are not specifically limited to a single layer or a multilayerstructure. The nitride semiconductor layer structure 11 includes a lightemitting layer 8 as the active layer. The active layer has a single(SQW) or multiquantum well structure (MQW). The following descriptionwill describe an example of the nitride semiconductor layer 11.

A lamination structure is formed on the growth substrate to interpose aprimary layer of nitride semiconductor such as a buffer layer (e.g., alow-temperature growth thin film GaN and a GaN layer) between thelamination structure and the growth substrate. In the laminationstructure, for example, an n-type contact layer of Si-doped GaN and ann-type multilayer structure of GaN/InGaN are laminated as the n-typenitride semiconductor layer. Subsequently, the active layer of InGaN/GaNMOW is laminated. In addition, for example, a p-type multilayerstructure of Mg-doped InGaN/AlGaN and a p-type contact layer of Mg-dopedGaN are laminated as the p-type nitride semiconductor layer. Also, thenitride semiconductor light emitting layer 8 (active layer) has aquantum well structure including a well layer, or barrier layers andwell layers, for example. Although a nitride semiconductor used for theactive layer may be doped with p-type impurities, it is preferable thenitride semiconductor is not doped or is doped with n-type impurities.The reason is that the non-doped or n-type doped nitride semiconductorcan provide a high output light emitting device. In the case where thewell layer contains Al, it is possible to obtain a wavelength shorterthan the wavelength 365 nm of the band gap energy of GaN. The wavelengthof light emitted from the active layer can be set to 360 to about 650nm, preferably 380 to 560 nm in accordance with the purposes,applications and the like of light emitting devices. InGaN is suitablyused for visible light and near-ultraviolet ranges as the composition ofthe well layer. In this case, GaN or InGaN is preferably used as thebarrier layer. Exemplary film thicknesses of the barrier layer and thewell layer are 1 nm to not more than 30 nm, and 1 nm to not more than 20nm, respectively. One well layer can compose the single quantum wellstructure. A plurality of well layers interposed between the barrierlayers and the like can compose the multi quantum well structure.

Subsequently, a mask forming a predetermined shape is formed on thesurface of the p-type semiconductor layer 7, and the p-typesemiconductor layer 7 and the active layer as the light emitting layer 8are etched. As a result, the n-type contact layer composing the n-typesemiconductor layer 6 is exposed in a predetermined location. As shownin FIG. 2, the n electrode 3A, the p electrode 13 and the pad electrode3B as a reflection electrode are formed on the n-type and p-type contactlayers. The protection film 14 is formed on the surface of the device soas to expose electrode coupling portions. Thus, the nitridesemiconductor light emitting device is produced.

Wiring Substrate

In the light emitting apparatus 1 shown in FIG. 1, as the wiringsubstrate 9 to be provided with the aforementioned light emittingdevices 10, a substrate can be used that has at least wires to beconnected to the electrodes of the devices on the surface of thesubstrate. The material of the substrate can be a crystalline substratesuch as a monocrystalline or polycrystalline substrate formed ofaluminum nitride, or a sintered substrate, as well as ceramics such asalumina, glass, a semimetal (e.g. Si) or metal substrate, ora laminationor composite member composed of them such as a substrate with analuminum nitride thin film formed on the surface of them. A metalsubstrate, a metallic substrate and a ceramic substrate are preferable,since they have high heat dissipation properties. In wiring patternformation, a metal layer is patterned by ion milling or etching. Anexample of wiring pattern can be provided by a patterned platinum thinlayer formed on the aforementioned aluminum nitride substrate. Inaddition, a protection film such as SiO₂ thin film or the like can beformed on the surface side of the substrate where the wiring pattern isformed. A substrate to be provided with the light emitting device is notlimited to a wiring substrate to be connected to the electrodes of thelight emitting device. A substrate without wiring pattern may be used.For example, in the case where the electrode formation surface side ofthe light emitting device serves as a main light emission side, thesubstrate side of the light emitting device may be mounted on thesubstrate without wiring pattern, and the electrodes of the device maybe connected to terminals of the apparatus by wires. In the arrangementof the substrate and the covering member, the covering member can bearranged on the substrate as shown in the illustrated the light emittingapparatus. Additionally, the covering member may cover the side surfacesof the substrate.

Transparent Member

The light emitting apparatus 1 shown in FIG. 1 includes the lighttransparent member 15 that allows light from the light emitting device10 to pass through the light transparent member 15. It is preferablethat the light transparent member 15 is a light conversion member thatcan convert the wavelength of at least a part of the passing light, andcontains the wavelength conversion member. Thus, when primary light fromthe light source passes through the light transparent member 15, thephosphor as the wavelength conversion member is excited wherebyproviding secondary light with a wavelength different from thewavelength of the main light source. As a result, the color of thesecondary light is mixed with the color of the primary light that is notconverted in wavelength. Therefore, it is possible to provide outgoinglight with a desired color.

The light emitting device 10 is enclosed by the light transparent member15 shown in FIG. 1 in plan view from the light emission surface 15 a. Inother words, as shown in FIG. 1, the side surfaces 15 c of the lighttransparent member 15 protrude outward relative to end surfaces 33 asthe side surfaces of the light emitting devices 10. Accordingly, ascompared with the case of FIG. 5 (embodiment 3), outgoing light from theoptically-connected light emitting device 10 can be directly received bythe light receiving surface 15 b wider than the upper surface of thelight emitting device 10. Therefore, luminous flux loss is small. Theprotrusion amount of the side surface 15 c of the light transparentmember 15 relative to the side surface of the light emitting device 10is not less than 3% to not more than 30% of the size of the lightemitting device, and more specifically not less than 5% to not more than15%. For example, in the light emitting apparatus according to theexample 1, as shown in FIG. 13, the protrusion width of the transparentmember 15 at the ends is about 50 μm.

As the aforementioned transparent member included in the lighttransparent member together with the wavelength conversion member, asimilar material to the later-described covering member can be used. Forexample, resins, glass, and inorganic substances can be used. Also, aformed or crystalline member of the later-described wavelengthconversion member may be used. In the case where the light transparentmember has a plate shape, it is preferable that both the light emissionsurface and the light receiving surface are substantially flat and thatthe both opposed surfaces are parallel to each other so that lightsuitably travels from the light receiving surface to the light emissionsurface. However, the present invention is not limited to this shape.The light emission surface and the light receiving surface are notlimited to a flat surface. The light emission surface and the lightreceiving surface can entirely or partially have a curved surface aswell as a planar shape such as an uneven surface. The light emissionsurface and the light receiving surface are not limited to a planarshape, but can have various forms and shapes, for example, a shape forfocusing or dispersing light such as an optical shape (e.g., lensshape).

As for the wavelength conversion function of the light transparentmember, the light emitting apparatus can emit mixed color light bymixing light from the light emitting device and light converted from thelight. In addition, the light emitting apparatus can emit secondarylight converted from primary light from the light emitting device, forexample, can emit light converted from ultraviolet light from the lightemitting device or mixed color light by mixing a plurality of convertedlight colors.

Specifically, the light transparent member 15, which has the wavelengthconversion function, can be composed of a glass plate with a lightconversion member; a phosphor crystal of light conversion member, or asingle crystal, polycrystal, amorphous substance or ceramic having thephase of the phosphor crystal; a sintered substance, aggregatedsubstrate or porous material of phosphor crystal particles andtransparent member suitably added to the phosphor crystal particles; amember with a transparent member (e.g., resin) mixed to or impregnatedwith them; or a transparent member containing phosphor particles (e.g.,a transparent resin formed member, etc.). It is preferable that thelight transparent member is composed of an inorganic material ratherthan organic materials such as resin in terms of thermal resistance.Specifically, the light transparent member is preferably composed of atransparent inorganic material that contains a phosphor. In particular,in the case where the light transparent member is composed of a sinteredsubstance of a phosphor and an inorganic substance (binding material),or is formed from a sintered substance or single crystal of phosphor,the reliability is increased. In the case where the later-discussed YAG(yttrium aluminum garnet) phosphor is used, it is preferable that thelight transparent member is a YAG/alumina sintered substance usingalumina (Al₂O₃) as biding material (binder) as well as a YAG singlecrystal and a high purity YAG sintered substance in terms ofreliability. Although the shape of the light transparent member 15 isnot specifically limited, the light transparent member 15 is formed in aplate shape in the embodiment 1. In the case of the plated shaped lighttransparent member, the light transparent member has high couplingefficiency with the light outgoing surface of the light emitting device10 formed in a plate shape, and additionally the light outgoing surfacecan be easily arranged substantially in parallel to the main surface ofthe light transparent member 15. In addition to this, in the case wherethe light transparent member 15 has a substantially constant thickness,uneven distribution of the constituent wavelength conversion member canbe suppressed. As a result, it is possible to substantially uniform thewavelength conversion amount of the light that passes through the lighttransparent member 15, and to stabilize the mixed color ratio.Consequently, it is possible to suppress part-to-part color unevennessin the light emission surface 15 a. For this reason, in the case where aplurality of light emitting devices 10 are arranged under one lighttransparent member 15, it is possible to provide high luminance lightemission with less unevenness caused by arrangement of the lightemitting devices 10 in luminance and in color distribution in the lightemission surface. It is preferable that the thickness of the lighttransparent member 15, which has the wavelength conversion function, isnot less than 10 μm and not more than 500 μm, and more preferably notless than 50 μm and not more than 300 μm in terms of light emissionefficiency and color adjustment.

A phosphor of YAG activated by cerium and a phosphor of LAG (lutetiumaluminum garnet) can be given as examples of typical phosphors to beused for a wavelength conversion member that can be suitably combinedwith a blue light emitting device to emit white light. In particular, inthe case of high luminance and long duration use, it is preferable that(Re_(1-x)Sm_(x))₃(Al_(1-y)Ga_(y))₅O₁₂:Ce (where, 0≤x≤1, 0≤y≤1, and Re isat least one element selected from the group consisting of Y, Gd, La andLu) or the like is employed. Also, a phosphor can be employed thatcontains at least one selected from the group consisting of YAG, LAG,BAM, BAM:Mn, (Zn, Cd)Zn:Cu, CCA, SCA, SCESN, SESN, CESN, CASBN, andCaAlSiN₃:Eu.

The light emitting apparatus 1 may include a plurality of wavelengthconversion members or a plurality of light transparent members that havethe function of the wavelength conversion member. For example, theaforementioned light conversion member can include two or more types ofmixed phosphors. In addition to this, the light emitting apparatus 1 caninclude a light transparent member that has a plurality of wavelengthconversion members for converting a wavelength to other wavelengthsdifferent from each other or include a plurality of light transparentmembers have the function. For example, the light emitting apparatus 1can include a laminated member of the light transparent members. Also,the light emitting apparatus 1 can include a light transparent memberthat includes one type of wavelength conversion member or have thefunction of the one type of wavelength conversion member, and a lightconversion portion separated from the light transparent member that hasa light conversion member on a light outgoing window portion of thelight emitting apparatus or on a light path from the light outgoingwindow portion to the light sources (e.g., between the light transparentmember and the light emitting devices, in the binding member), orbetween the light emitting devices and the covering member. In the casewhere a nitride phosphor is used that emits yellow to red light, areddish component can be increased. In this case, it is possible toprovide lighting with high general color rendering index Re, or an LEDwith electric bulb color. Specifically, the amount of phosphor with achromaticity point different from a light emitting device on thechromaticity diagram of CIE is adjusted based on the light-emissionwavelength of the light emitting device. As a result, it is possible toemit light at any point on the chromaticity diagram on the line that isconnected between the phosphor and the light emitting device. Inaddition to this, examples of the phosphors can be given by nitridephosphors, which convert near-ultraviolet to visible light into light inyellow to red ranges, oxynitride phosphors, silicate phosphors,L₂SiO₄:Eu (L is alkaline-earth metals), in particular(Sr_(x)Mae_(1-x))₂SiO₄:Eu (Mae is alkaline-earth metals such as Ca andBa), and the like. Examples of the nitride group phosphors and theoxynitride phosphors can be given by Sr—Ca—Si—N:Eu, Ca—Si—N:Eu,Sr—Si—N:Eu, Sr—Ca—Si—O—N:Eu, Ca—Si—O—N:Eu, Sr—Si—O—N:Eu, and the like.Examples of the alkaline-earth silicate phosphor can be represented bygeneral formula LSi₂O₂N₂:Eu, general formulaL_(x)Si_(y)N_((2/3x+4/3y)):Eu, orL_(x)Si_(y)O_(z)N_((2/3x+4/3y−2/3z)):Eu (L is Sr, Ca, or Sr and Ca).

In the light emitting apparatus, the number of the light emittingdevices 10 under one light transparent member 15 is not specificallylimited. However, it is preferable that the light emitting apparatusincludes two or more light emitting devices 10, which can emit lightpassing through one light transparent member 15. The reason is that itis possible to increase the total amount of light flux that travelstoward the light receiving surface 15 b, and as a result it is possibleto increase the luminance of emitted light from the light emissionsurface 15 a. In the case where a plurality of light emitting devices 10are installed, the light emitting devices 10 can be joined to eachother. However, in this case, it is preferable that the light emittingdevices 10 are spaced at a suitable interval away from each other. Theinterval distance between the light emitting devices 10 can be suitablydesigned in consideration of the light directivity and the heatdissipation property of the light emitting apparatus, and the mountaccuracy of the light emitting devices. For example, the intervaldistance can be not more than 10% of the size of the light emittingdevice.

Covering Member and Sealing Member

As shown in FIG. 1, the sealing member 26 covers parts of the lighttransparent member 15. Specifically, the sealing member 26 covers atleast the side surfaces 15 c of the light transparent member 15.

Resin materials as a base material of the sealing member 26 are notlimited as long as they are transparent. Silicone resin compositions,denatured silicone resin compositions and the like are preferably used.However, transparent insulating resin compositions may be used such asepoxy resin compositions, denatured epoxy resin compositions and acrylicresin compositions. Also, excellent weather-resistant sealing membersmay be used such as hybrid resins containing at lease one of theseresins. Also, excellent light-resistant inorganic material may be usedsuch as glass and silica gel. Also, the sealing member can be formed ina desired shape on the light emission side to provide a lens effect. Inthis case, it is possible to focus light from the light emitting chips.In the embodiment 1, silicone resin is used as the sealing member interms of thermal resistance and weather resistance.

In the embodiment 1, the sealing member 26 includes the light reflectivematerial 2 in the aforementioned resin. It is preferable that thesealing member 26 includes at least two types of resin materials withdifferent refractive indices from each other. In this case, it ispossible to improve reflective ability, and to suppress a light leakagecomponent that passes through the resin and is leaked to a neighbormember. That is, it is possible to direct light toward a desireddirection. To effectively achieve the aforementioned effects, at leastone type of resin material with less light absorption is included inresin as the base material, i.e., in the silicone resin in theembodiment 1. In the case where the sealing member 26 includes the lightreflective material, the reflectivity of the sealing member 26 isincreased. In addition, in the case where the sealing member 26 suitablyincludes transparent particles, reflection by the transparent particlescan provide a covering member with low light absorption and low loss. Inother words, outgoing light from the LED chips is reflected by themember 26 that covers the periphery of the LED chips, and is guidedtoward the LED chips or the light transparent member 15. The sealingmember 26 may include one type of resin, for example, silicone resin.For example, two-component silicone resin can be used in that a maincomponent and a hardener are mixed.

The light reflective material 2 included in the sealing member or thecovering member 26 is one selected from the group consisting of oxidesof Ti, Zr, Nb, Al and Si, or at least one selected from the groupconsisting of AlN and MgF. Specifically, the light reflective material 2is at least one selected from the group consisting of TiO₂, ZrO₂, Nb₂O₅,Al₂O₃, MgF, AlN and SiO₂. It is preferable that the light reflectivematerial included in the aforementioned member 26, in particular in thetransparent resin, is one selected from the group consisting of oxidesof Ti, Zr, Nb, and Al in particular as the transparent particles. Inthis case, the transparency and reflexivity of the light reflectivematerial, and the refractive-index difference between the lightreflective material and the base material are increased. The coveringmember may be composed of a formed member formed from the aforementionedlight reflective materials. Specifically, the covering member may be aporous material such as an aggregated member or sintered member of theaforementioned particles that aggregate together. Also, the coveringmember may be a formed member formed by a sol gel process. The coveringmember of such a porous material is preferable. The reason is that,since the refractive-index difference between the aforementioned lightreflective material and air within porous can be great, the lightreflexivity of the covering member can be improved. In comparisonbetween the covering member of porous material and the covering memberthat includes a base material such as the aforementioned resins, theyare likely to be different in formability into a desired shape, sealingability and airtight ability. If a light emitting apparatus is providedthat includes the covering member containing either or both materials,it is preferable that the covering member contains the aforementionedbase material. Also, in consideration of the characteristics of bothtypes of covering members, the covering member can be composed of acomplex formed member formed of the both types of covering members. Forexample, the covering member formed in a desired shape is impregnatedwith resin from the outside surface side so that the resin penetratesthe outside surface of the covering member at a depth. In this case, thethus-formed covering member can seal the light emitting devices,improves airtightness, and achieves high reflective performance on theinside surface side as the light emitting device side that is providedby the porous property. The covering member or sealing member, or asurrounding member composed of the covering member does not necessarilycompletely or airtightly seal the light emitting devices. The insideparts of the covering member or the surrounding member may communicatewith the outside. The covering member or the surrounding member may haveair transparency. The covering member or the surrounding member is onlyrequired at least to prevent leakage of light, in particular, to preventleakage of light in the light emission direction.

In the covering member including the light reflective material inaforementioned base material, the leakage distance of light varies inaccordance with the content concentration or density of the lightreflective material. For this reason, it is preferable that the contentconcentration or density is suitably adjusted in accordance with theshape and the size of the light emitting apparatus. For example, in thecase where the light emitting apparatus is relatively small, thethickness of the covering member is required to be small which coversthe light emitting device and the light transparent member. In otherwords, it is preferable that the light emitting apparatus includes alight transparent material at high concentration to allow the thinmember to suppress light leakage. On the other hand, in productionprocesses such as preparation of basis material of the covering membercontaining the light reflective material, and application and formationof the basis material, if high concentration of the light reflectivematerial in the basis material makes the production difficult, theconcentration of the light reflective material in the basis material maybe suitably adjusted. Although the covering member has been describedthat includes the base material, same goes for the aforementioned porousmember. As an example, according to the later-discussed comparativeexperiment, it is suitable that the content concentration is not lessthan 30 wt %, and the thickness is not less than 20 μm. These ranges canprovide high luminance light with high directivity emitted from thelight emission surface. Also, in the case where the concentration of thelight reflective material is high, the heat dissipation property can beincreased. As another example, the content concentration of the lightreflective material in the silicone resin can be not less than more than20 wt % and not more than 30 wt %. This range is preferable since resincan have an appropriate viscosity, and underfill by the sealing memberor covering member 26 can be easily formed.

Covering Area

As discussed above, the outgoing light from the light emitting devices10 passes the light receiving surface 15 b of the light transparentmember 15, travels in the light transparent member 15, and then outgoesfrom the light emission surface 15 a. Thus, the following operation andworking effects can be provided by covering at least the side surfaces15 c of the light transparent member 15 with the sealing member 26.Firstly, it is possible to prevent that light leaks from the sidesurface 15 c areas. Secondly, it is possible to suppress outwardemission from the side surface 15 c side of light with considerablecolor difference relative to light emission from the light emissionsurface 15 a, and therefore to reduce color unevenness in the entirelight emission color. Thirdly, since outward light emission area isrestricted by reflecting light that travels toward the side surfaces 15c toward the light outgoing side, it is possible to increase thedirectivity of emitted light and to increase the luminance of the lightemission surface 15 a. Fourthly, since heat generated from the lighttransparent member 15 is conducted to the sealing member 26, it ispossible to increase the heat dissipation property of the lighttransparent member 15. In the case where the light transparent member 15contains the wavelength conversion member, since the wavelengthconversion member generates heat much, this configuration is veryeffective.

As long as the sealing member 26 covers the side surfaces 15 ccontiguous to the light emission surface 15 a of the light transparentmember 15, i.e., the side surface 15 c side that extends in parallel tothe thickness direction, and the light emission surface 15 a is exposedfrom the sealing member 26, the external shape of the sealing member 26is not specifically limited. For example, the sealing member 26 may beconfigured protruding outward relative to the light emission surface 15a (this embodiment) or recessed (embodiment 3). On the other hand, inthe embodiment 1, as shown in FIG. 1, the external surface of thesealing member 26 is configured extending along the surface of the lightemission surface 15 a, in other words, the exposed surface of thecovering area of the sealing member 26 is substantially coplanar withthe surface of the light emission surface 15 a. Accordingly, it ispossible to provide easy production and to improve yields. In addition,since the side surfaces 15 c are substantially entirely covered, it ispossible to increase the heat dissipation property of the lighttransparent member 15.

In the embodiment 1, the sealing member 26 covers a part of the lightreceiving surface 15 b as well as the side surfaces 15 c of the lighttransparent member 15. Specifically, as shown in FIG. 1, space betweenthe light transparent member 15 and the wiring substrate 9 is filledwith the sealing member 26 so that the peripheries of the light emittingdevices 10 are covered by the sealing member 26. Specifically, thesealing member 26 covers an area of the light receiving surface 15 b ofthe light transparent member 15 except areas that face the lightemitting devices 10. In this configuration, the optically-coupling areasbetween the light emitting devices 10 and the light transparent member15, and the covering area of the sealing member 26 are provided in thelight receiving surface of the light transparent member. As a result,light can be guided limitedly through the optically-coupling areas sothat primary light from the light emitting devices 10 can be highlyefficiently guided from the optically-coupling areas toward the lighttransparent member 15 side. Also, the sealing member 26 in the coveringareas reflects, toward the light outgoing side, light that travelstoward the light receiving surface side of the light transparent member.Accordingly, it is possible to suppress loss of primary light thatenters the light transparent member. Such loss may occur due to lightabsorption by the wiring substrate 9 and the like. As shown in FIG. 1 orthe like, in the case where a plurality of light emitting devices 10 arejoined to one light transparent member 15, it is preferable that spacebetween the light emitting devices is also filled with the sealingmember 26 so that the sealing member 26 covers separation areas locatedbetween the junction areas of the light receiving surface 15 b to whichthe light emitting devices are joined. The light transparent member 15is likely to hold heat generated right above the junction areas to whichthe light emitting devices 10 are joined. This configuration can improveheat dissipation of the aforementioned separation areas. In addition, itis preferable that the light transparent member 15 has the protrusionareas that protrude outward relative to the light emitting devices 10,and the protrusion areas on the light receiving surface 15 b side arecovered by the sealing member 26 as discussed above. The reason is thatthis configuration facilitates heat dissipation toward the outerperipheries of the light transparent member 15 and the light emittingdevice 10. Since the covering areas of the light transparent member 15are increased which are covered by the sealing member 26, it is possiblefurther improve the heat dissipation from the light transparent member15.

Additive Member

In addition to the light reflective material 2 and the light conversionmember, appropriate members such as viscosity-increasing agent can beadded to the covering or sealing member 26, and the light transparentmember 15 in accordance with applications. Thus, the light emittingapparatus can be provided that has desired light emission color,directional characteristics, and the color of these members or theapparatus surface, for example the external surface of the coveringmember can be colored in black in order to increase the contrast withenvironmental light. Similarly, various types of coloring agents can beadded as a filter material that provides a filter effect cutting offexternal entering light and light with unnecessary wavelength from thelight emitting devices.

Adhesive Material

An adhesive material 17 is interposed on the boundary between the lightemitting device 10 and the light transparent member 15 so that the lightemitting device 10 and the light transparent member 15 are fastened. Theadhesive material 17 is preferably composed of a material that caneffectively guide light emitted from the light emitting device 10 towardthe light transparent member 15 side, and can optically couple the lightemitting device 10 and the light transparent member 15 to each other. Anexample of material of the adhesive material can be provided by theresin material used for aforementioned members. As an example, atransparent adhesive material is used such as silicone resin. Also, thelight emitting device 10 and the light transparent member 15 can befastened to each other by crystal adhesion by thermocompression bondingor the like.

Light Emitting Apparatus

The aforementioned light emitting devices 10 are installed on the wiringsubstrate 9 in a flip chip mounting manner. The aforementioned lighttransparent member and the covering member are arranged on the lightemitting devices 10 and the wiring substrate 9. Thus, the exemplarylight emitting apparatus 1 shown in FIG. 1 is provided. As an example ofproduction method of the light emitting apparatus, a production methodis described with reference to FIGS. 3A-3C. First, as shown in FIG. 3A,the bumps 24 are formed on the wiring substrate 9 or the light emittingdevices 10 in accordance with the flip chip mounting pattern.Subsequently, the light emitting devices 10 are mounted by the bumps 24in a flip chip mounting manner. In this example, one LED chip isarranged for an area corresponding to one light emitting apparatus.However, the number of installed chips can be suitably changed inaccordance with the size of the light emission surface and the size ofthe light transparent member. Also, the light emitting devices 10 may bemounted by eutectic adhesion. In this case the junction area between thewiring substrate 9 and the light emitting device 10 can be large tofacilitate heat dissipation. Therefore, it is possible to improve heatdissipation.

Also, in a process shown in FIG. 3B, silicone resin as the adhesivematerial 17 is applied onto the back surface side of the light emittingdevice 10 (onto the sapphire substrate back surface, or onto the nitridesemiconductor exposure surface in the case where the substrate isremoved by LLO), and the light transparent member 15 is laminated on thelight emitting device 10. Subsequently, the silicone resin 17 isthermally cured so that the light emitting devices 10 and the lighttransparent member 15 are adhered on each other.

In addition, screen printing is conducted in a process shown in FIG. 3C.In screen printing, a metal mask is arranged on the wiring substrate 9.Resin is applied that forms the sealing member 26, and is spread by asqueegee. The surface of the light transparent member 15 is wiped by thesqueegee so that the surface of the sealing member 26 extends along thesurface of the light transparent member 15, in other words, so that boththe surfaces are substantially coplanar with each other. Alternatively,the surface of the sealing member 26 may be flattened by its own weightwithout using the squeegee after resin 26 potting. Alternatively, thesealing member 26 may be formed by transfer molding. After the resin 26is cured, the metal mask is removed, and the resin and the wiringsubstrate are cut at predetermined positions (for example, dashed linesin FIG. 3C) into a sub-mount substrate size in dicing.

However, the method for arranging the resin 26 is not specificallylimited which covers the peripheries of the light emitting devices 10.For example, a package may be formed as a frame member that formsboundaries of an area where the resin 26 is arranged, and may be filledwith the resin 26. The frame member can be removed after the lightemitting apparatus is formed. Alternatively, the frame member may remainif the softness of resin for filling the inside of the frame memberrequires the frame member remaining. The frame member serves the outlineof the light emitting apparatus, and can increase the strength of thelight emitting apparatus. Also, the wiring substrate may have a cavityto simplify the process. Also, the light emitting device may be directlymounted onto a predetermined installation location of the light emittingapparatus. In other words, the sub-mount may be eliminated. Also, eachof the aforementioned sub-mount substrates separated from each other canbe the light emitting apparatus. Alternatively, a lens or the like maybe adhered to and seal each of the aforementioned sub-mount substrates.In this case, each sub-mount with the lens can be the light emittingapparatus.

Embodiment 2

In an embodiment 2, the light emitting devices 10 are arranged relativeto the light transparent member 15 in another exemplary arrangement.FIG. 4 is a schematic cross sectional view showing a light emittingapparatus 20 according to the embodiment 2. In the light emittingapparatus 20 shown in FIG. 4, the side surfaces 15 c of the lighttransparent member 15 are substantially coplanar with the end surfaces33 of the light emitting devices 10, in other words, the side surfacesof the light transparent member 15 and the light emitting device 10 aresubstantially coplanar with each other. This arrangement can preventthat color unevenness is likely to occur in a part where the lighttransparent member protrudes relative to the device in the foregoingembodiment 1, i.e., outer peripheral parts of the light transparentmember, due to an insufficient amount of light from the light emittingdevice. Here, “substantially coplanar” in this specification refers toapproximately coplanar in terms of the aforementioned functions. Forexample, “substantially coplanar” can be ±10% of the size of the lighttransparent member or the light emitting device of the coplanar lightemitting apparatus. This is not limited to “substantially coplanar” ofthe light transparent member with the light emitting device, but can beapplied to “substantially coplanar” of the light emission surface of thelight transparent member with the external surface of the coveringmember that surrounds the light emission surface.

Embodiment 3

FIG. 5 shows a schematic cross-sectional view showing a light emittingapparatus 30 according to an embodiment 3. In the light emittingapparatus 30 shown in FIG. 5, the light transparent member 15 islaminated on parts of the light emitting devices 10, in other words, theside surface 15 c of the light transparent member 15 is located insidethe end surface 33 of the light emitting device 10.

In arrangements shown in FIG. 1 (embodiment 2), FIG. 4 (embodiment 3),and FIG. 5 (this embodiment), the periphery of the light emissionsurface 15 a is covered by the sealing member 26 in a plan view from thelight outgoing side. Accordingly, light is not emitted from the outsideareas of the sealing member 26 containing the light reflective material2. In other words, the light emission area of the light emittingapparatus substantially depends on the light emission surface 15 a ofthe light transparent member 15. For this reason, in the arrangementaccording to the embodiment 1 shown in FIG. 1, since the light emissionsurface 15 a can be large as compared with the light emitting device,the amount of light flux and the output from the light emittingapparatus can be increased. In the example according to this embodimentshown in FIG. 5, the light emission area is reduced, and the lightemission surface is small as compared with the light emitting device.Accordingly, it is possible to further even the mixed color ratio tosubstantially constant. Therefore, it is possible to emit light withfurther reduced color unevenness. In addition, since the light emissionarea is reduced, it is possible to increase relative luminance. Also,the arrangement shown in FIG. 4 is a kind of middle arrangement betweenthe examples shown in FIGS. 1 and 5. Therefore, it is possible to emitlight with light flux/luminance and color distribution in balance.

Embodiment 4

Also, it is important that the sealing member 26 is arranged at least onthe periphery of the light emission surface 15 a of the lighttransparent member 15, in other words, the sealing member 26 is formedin surface contact with the side surfaces 15 c to restrict the lightemission area of the light emitting apparatus to the light emissionsurface 15 a. Other covering areas by the sealing members 26 are notspecifically limited. A light emitting apparatus 40 according to anembodiment 4 is different from the embodiments 1 to 3 from the viewpointof the covering area of the sealing member 26 for covering the lightemitting device 10. FIG. 6 is a schematic cross sectional view showing alight emitting device 40 according to the embodiment 4. In the lightemitting apparatus 40, other structures except a covering area of asealing member 26 b is substantially similar to the embodiment 1 to 3,and therefore similar components are attached with the same referencenumerals and their description is omitted.

The covering area of the sealing member 26 b according to the embodiment4 for covering the light emitting device 10 is different from theembodiments 1 to 3. That is, the sealing member 26 b covers only outerparts away from the end surfaces 33 of the light emitting devices 10.Accordingly, exposed parts are spaced away from each other that are notcovered and are exposed from optically connecting parts and electricallyand physically connecting parts. The optically connecting parts of thelight emitting device surfaces are connected to the aforementioned lighttransparent member. The electrically and physically connecting parts ofthe light emitting devices are electrically and physically connected tothe wiring substrate. The spaced areas between the two or more lightemitting devices 10 are not filled with the sealing member 26 b so thathollow parts are formed. In particular, in the example shown in FIG. 6,the sealing member 26 b outside the light emitting devices 10 is spacedaway from the end surfaces 33 of the light emitting devices 10.Specifically, the sealing member 26 b is arranged on the end surface 33sides of the light emitting devices 10 in substantially parallel to theend surfaces 33, and is spaced away from the end surfaces 33. That is,the light emitting device 10 is surrounded by the light transparentmember 15 and the wiring substrate 9 in the vertical direction, and bythe sealing member 26 b in the horizontal direction. Thus, interiorspace is formed surrounded by these surrounding members, and cavitiesare formed on the peripheries of the light emitting devices 10. It ispreferable that the covering member is formed as a surrounding memberthat surrounds the light receiving surface side area of the lighttransparent member and the light emitting devices, and covers parts ofthe wiring substrate or is arranged on the wiring substrate as discussedabove. Also, it is preferable that the covering member is spaced awayfrom the light emitting devices so that the interior area is formedinside the surrounding members as discussed in this embodiment. In thiscase, as illustrated, it is preferable that the surrounding member isformed as an outer case member that includes the light transparentmember as a window portion of the surrounding member and a lightemission surface of the outer case member, and is formed as an outercase member the light emission surface of which is arranged on the frontsurface side in the light outgoing direction.

In the case of the aforementioned configuration, that is, in the casewhere the interior area is formed by the aforementioned surroundingmember, it is possible to suppress light loss caused by covering theaforementioned exposed part of the light emitting device (e.g., lightabsorption by the sealing member). That is, it is possible to increasethe light amount of the aforementioned optically-coupling part.Therefore, the light emitting apparatus can have high output andluminance. In this case, it is preferable that, in order to increase therefractive-index difference between the aforementioned interior spaceand the light emitting device, the aforementioned interior space isairtightly sealed to provide high refractive-index difference betweenthe device and air or gas at the exposed part. Also, in the case where aplurality of light emitting devices are optically coupled to one lighttransparent member, it is preferable that hollow parts are similarlyformed between the devices. Also, in the case where the light emissionsurface of the light transparent member is sufficiently large ascompared with the aforementioned light emitting device or itsoptically-coupling part, the aforementioned base materials of the lighttransparent member and the covering member such as resin can be suitablyemployed. In this case, the light receiving surface of the lighttransparent member has the optically-coupling area coupled to thedevice, and a filling member coupling area coupled to the transparentmember with which the interior space is filled. Accordingly, light fromthe device enters the aforementioned filling member in addition to apath where the light from the device directly enters theoptically-coupling area. As a result, light can enter the lighttransparent member through the filling member coupling area. Therefore,the light emission surface can be larger than the device. In addition,the shape of the sealing member 26 b is simple. Accordingly, it is alsopossible to provide the light emitting apparatus 40 in that the sealingmember 26 b is produced separately from the light transparent member 15,and coupled to the light transparent member 15.

EXAMPLE 1

In order to evaluate the advantages of light emission properties of thelight emitting apparatuses according to the embodiments, the followingexamples are produced. As shown in FIG. 1, the light emitting apparatus1 according to an example 1 includes one light transparent member 15,and the two LED chips with an approximately square of about 1 mm×1 mm.The sealing member 26 covers parts of the light transparent member 15and the light emitting device 10. The light transparent member 15 has aplate shape. The light emission surface 15 a, and the light receivingsurface 15 b opposed to the light emission surface 15 a have arectangular shape of about 1.1 mm×2.2 mm. Also, the thickness is 150 μm.Also, the sealing member 26 is formed of silicone resin containing TiO₂particles. As shown in FIG. 1, the sealing member 26 is formed coveringperipheral parts of the light emission surface 15 a, specifically, theside surfaces 15 c of the light transparent member 15 in plan view fromthe light outgoing side of the light emitting apparatus 1, and extendingplanarly along the light emission surface 15 a. That is, in the lightemitting apparatus 1, the light emission surface 15 a serves as the mainlight emission surface, and the periphery of the light emission surface15 a is covered by the sealing member 26 to suppress outward lightemission from the covering areas. The light transparent member 15 coversthe optically-coupling areas in the light receiving surface 15 b coupledto the light emitting devices 10, and fills space between the wiringsubstrate 9 and the light transparent member 15 to cover the sidesurfaces and the mount side of the light emitting device 10.

COMPARATIVE EXAMPLE 1

FIG. 7 is a schematic cross-sectional view showing a light emittingapparatus 200 according to a comparative example 1. The light emittingapparatus 200 has a covering area of a sealing member 26 for coveringthe light transparent member 15, which is only substantial differencefrom the light emitting apparatus 1 according to the example 1. That is,the light transparent member 15 protrudes upward relative to the surfaceof the sealing member 26. The sealing member 26 does not cover the sidesurfaces 15 c of the light transparent member 15. Thus, the sidesurfaces 15 c are externally exposed.

As discussed above, as for production methods of the light emittingapparatus according to the example 1 and the comparative example 1,after the light transparent member 15 is laminated the light transparentmember 15 is covered by the sealing member 26 in the example 1, whileafter the sealing member 26 is previously formed the light transparentmember 15 is attached to the sealing member 26 in the comparativeexample 1. Thus, the sealing member 26 according to the comparativeexample 1 does not cover the side surfaces 15 c of the light transparentmember 15, in other words, the side surfaces 15 c are externallyexposed. As a result, in the light emitting apparatus 200 according tothe comparative example 1, when outgoing light from the light emittingdevices 10 pass through the light receiving surface 15 b of the lighttransparent member 15, the outgoing light travels in the lighttransparent member 15, then outgoes from the exposed side surfaces 15 cand the light emission surface 15 a. That is, the light transparentmember 15 of the light emitting apparatus 200 has a configurationsimilar to the light emitting apparatus 100 shown in FIG. 10, in otherwords, outgoing light from the light transparent member 15 is emittednot only from the light emission surface 15 a but also from the sidesurfaces 15 c side. For this reason, the difference between the lightcolors emitted from the light emission surface 15 a and the side surface15 c is visually perceivable.

The following description describes the light flux, luminance andchromaticity distribution properties of the light emitting apparatusesaccording to the example 1 and the comparative example 1.

As for light flux, the maximum values of the example 1 and thecomparative example 1 are 167 [Lm] (chromaticity ΦY about 0.339) and 166[Lm] (chromaticity ΦY about 0.322), respectively. Accordingly, theexample 1 and the comparative example 1 have a substantially equal lightflux property. Therefore, it is found that almost no light cut-offeffect occurs by covering the side surface 15 b of the light transparentmember 15 with the sealing member 26 in the example 1.

As for luminance, the maximum luminance and the average value of averageluminance of light emission are 6086 [cd/cm²] and 3524 [cd/cm²],respectively, in the example 1, while the maximum luminance and theaverage value of average luminance of light emission are 3952 [cd/cm²]and 2500 [cd/cm²], respectively. That is, the luminance of the example 1improves about 40% compared with the comparative example 1. FIG. 8 showsthe chromaticity distribution properties in the light emittingapparatuses of the example 1 and the comparative example 1. In both theexample 1 and the comparative example 1, the relative maximum value ofcolor temperature lies at a part where the viewing angle is small, i.e.,on the optic axis. The color temperature decreases as the absolute valueof the light outgoing angle is getting larger. However, in thecomparative example 1, the color temperature difference between agreater angle and a lower angle is remarkably large. Specifically, thecolors of a greater angle and a lower angle are different so that colorunevenness is perceived. The color temperature difference in the example1 is very small as compared with the comparative example 1. Although thecolor temperature in the comparative example 1 draws a steep curve therelative maximum value of which lies at the optic axis, the colortemperature in the example 1 draws a gentle curve. In other words, thecolor temperature difference in the example 1 is small over the wholeviewing angles, therefore, color unevenness is remarkably reduced. Sinceoutgoing light in the transverse direction causes color unevenness inlight emission of the entire light emitting apparatus irrespective ofthe light flux of the outgoing light to a greater or lesser extent, itis preferable that the sealing member 26 guides a component of the lighttraveling in the transverse direction toward the light emission surface15 a side as discussed above. We consider the advantages of the sealingmember 26 in terms of luminance as follows.

In the light emitting apparatus that covers the side surfaces 15 c ofthe light transparent member 15 according to the present invention(hereafter occasionally referred to as “covered type”), as the thicknessof the light transparent member 15 increases, the covering area of thesealing member 26 for covering the side surfaces 15 c accordinglyincreases. As discussed above, almost no effect occurs due to the lightabsorption by the sealing member 26 on the side surfaces. Accordingly,even in the case where the thickness of the light transparent member 15increases, a component of light traveling in the thickness direction isguided toward the light emission surface 15 a side. As a result, lightwill be emitted substantially only through the light emission surface 15a outward of the light emitting apparatus. That is, the luminance of thelight emission surface 15 a does not depend on the thickness of thelight transparent member 15, and can be substantially constant on everyoccasion.

On the other hand, in the light emitting apparatus as discussed in thecomparative example 1 that does not cover the side surfaces 15 c of thelight transparent member 15 (hereafter occasionally referred to as“non-covered type”), as the thickness of the light transparent member 15increases, the ratio of a component of light outgoing from the sidesurfaces or the outgoing light outgoing from the side surfacesincreases. In other words, the ratio of the light emitted from the lightoutgoing surface as the light outgoing side decreases. That is, theluminance of the light outgoing surface decreases.

Verification is conducted to verify the extent to which the ratio of theoutgoing light from the light emission surface 15 a and the both sidesurfaces 15 c of the plate-shaped light transparent member, or a rangeof the thickness of the light transparent member 15 can effectivelyprovide a luminance increase effect by covering the side surfaces 15 c,in other words, can effectively provide a reflection effect on the sidesurfaces 15 c by the sealing member 26. In FIG. 9, on the assumptionthat light is not emitted from the light receiving surface 15 b as thebottom surface in both the covered type and the non-covered type, andthat light is uniformly emitted from the light emission surface 15 a andthe side surfaces 15 c in the non-covered type, the luminance of lightemitted from the light emission surface 15 a in each type is measured([luminance]=[light flux]/[the area of light emission surface]). Inaddition, on the assumption that the total light flux of the coveredtype decreases 10% as compared with the non-covered type, luminancevariation is shown in accordance with increase of the ratio of thethickness of the light transparent member 15 ([side surface ratio]=[thearea of both side surfaces]/[the area of the light emission surface]).The 10% decrease of light flux stated herein is a value in considerationof light absorption by reflection in the sealing member 26 in thecovered type. However, as discussed above, actually almost no lightabsorption occurs by the sealing member 26. The value is a generousestimate of light loss amount.

As shown FIG. 9, in the covered type, since the light emission area doesnot depend on the thickness of the light transparent member, theluminance is substantially constant. On the other hand, in thenon-covered type, as the thickness of the light transparent memberincreases, the amount of light emitted from the light emission surfacedecreases. Thus, the relative luminance decreases. Also, thickness ofthe light transparent member 0.04 mm or the side surface ratio about 12%provides substantially the same luminance in the covered type and thenon-covered type. In addition, thickness 0.02 mm or side surface ratioabout 5.2% provides light flux difference 5%. Accordingly, in the casewhere the thickness of the light transparent member is greater than thisvalue, it is found that the luminance of the covered type is higher thanthe non-covered type.

When this estimate is applied to the luminance properties of theaforementioned example 1 and the comparative example 1, it is found thata side surface ratio about 29% provides a luminance ratio at theaforementioned 5% light flux difference ([luminance of non-coveredtype]/[luminance of covered type]) about 134%. Also, as compared withluminance ratio at 0% light flux difference about 141%, the differencebetween the foregoing example 1 and the comparative example 1 is about0.01%, and the luminance ratio of the foregoing example 1 and thecomparative example 1 is about 141%. These values show good agreementwith each other.

As discussed above, since the comparison verification between thecovered type and the non-covered type based on the aforementionedassumption shows good agreement between the properties of the example 1and the comparative example 1, it is found that this verification iseffective.

Thickness and Reflection Ability of Covering Member

As for the light reflective material 2 included in the sealing member26, in the light emitting apparatus 1 of the example 1, the siliconeresin includes TiO₂ as the light reflective material 2 to form thesealing member 26. The reflective ability of the sealing member 26 andthe light incoming depth into the sealing member 26 vary in accordancewith the content of the light reflective material in transparent resinand the thickness of the covering member 26. For example, an Al filmwith high reflectivity and a W film with low reflectivity are formed ona ceramic substrate similar to the example 1. Silicone resin is mixedand kneaded with the TiO₂ particles (mean particle diameter 0.2micrometer) similar to the example 1. Materials of the covering memberare prepared with ratios of 25%, 33% and 50% by weight relative to thesilicone resin. These materials are applied onto the aforementionedceramic substrate. These materials are coated by spin coating atapplication revolution numbers of 2000, 4000 and 6000 rpm. The resin isthermally cured. Thus, test samples are produced. The reflectivities ofthe test samples made from the materials at the application conditionsare measured in the direction perpendicular to the surface of the testsamples. Thus, it is possible to evaluate the aforementioned reflectiveability, the aforementioned light incoming depth, and the like.

For example, covering members with thicknesses of 20 μm and 70 μm aremade from a 50 wt % material at revolution numbers of 6000 and 2000 rpm.On the other hand, the reflectivities of covering members do not dependon the difference between Al and W, and are substantially constant. Asthe revolution number increases, in other words, as the thickness of themember is getting smaller, it is observed that the reflectivity tends toslightly decrease. For example, the reflectivity decreases from 94% to89% under the conditions of the aforementioned revolution number andmember thickness.

Also, in the cases of about 25 wt % and 33 wt %, the difference of thereflectivities between the aforementioned Al and W reflectivefilms[reflectivity of Al sample]−[reflectivity of W sample] is large. Inparticular, the difference tends to increase in a range of higherrevolution number. The difference and the difference in a range ofhigher revolution number of the test sample of 33 wt % are smaller thanthe test sample of 25 wt %. For example, in the test sample of 33 wt %and revolution number 2000 rpm, almost no difference exists between Aland W reflective films. Also, the reflectivity of the aforementionedtest sample of 33 wt % is lower than the aforementioned test sample of50 wt %. In addition, the reflectivity of the test sample of 25 wt % islower than the aforementioned test sample of 33 wt %. For this reason,the content of the reflective material can be not less than 30 wt %,preferably not less than 40 wt %, and more preferably not less than 50wt %. It is found that the thickness can be not less than 20 μm. Forthis reason, it is also found that thickness of the covering member inthis extent is sufficient around the outer peripheral parts of the lighttransparent member, in parts between the light transparent member andthe wiring substrate, in protrusion parts of the light transparentmember protruding relative to the device, in the device exposed parts,and in parts between devices.

In the light emitting apparatus 1 according to the example 1, thespacing distance between the opposed surfaces of the light transparentmember 15 and the wiring substrate 9 is not less than 100 μm.Accordingly, in the case where this spacing area is filled with thesealing member 26, the sealing member 26 will have a thickness withinthe aforementioned range. Therefore, it is ensured that light isreflected toward the light receiving surface 15 b side so that the lightabsorption effect by the wiring substrate 9 can be prevented.

EXAMPLE 2

Similar to the light emitting apparatus 1 shown in FIG. 6, an apparatusis produced that includes hollow parts around the light emitting devicesas follows.

Similar to the example 1, the light emitting devices are mounted on thewiring substrate, and the light transparent member is coupled to thelight emitting devices. In this example, the light transparent member islarger than the wiring substrate, and has a size about 2.2 mm×3.2 mm.The light transparent member is arranged enclosed in the wiringsubstrate. In addition, the light emitting devices are also arrangedenclosed in the wiring substrate. Subsequently, resin of the coveringmember according to the example 1 is applied to cover the side surfacesof the wiring substrate, and the side surfaces and parts of the lightreceiving surface of the light transparent member, and is formed bythermal curing. In this process, the side surfaces of the substrateallow the resin to serve as a weir so that the resin is held withoutentering the interior of the wiring substrate, that is, inner walls ofthe covering member are formed on the edges of the wiring substrate. Theresin covering the substrate side surfaces on the substrate outsidecovers the light receiving surface of the light transparent member thatprotrudes outward of the wiring substrate. Thus, the hollow parts areformed between the interior walls of the resin and the light emittingdevices. In this example, hollow parts are same as areas of the wiringsubstrate that protrude from the light emitting devices. The wiringsubstrate protruding parts and the hollow parts are formed around theouter peripheries of the light emitting devices at width 400 μm(distance from the light emitting device to the interior wall of theresin). Thus, the light emitting apparatus is produced which includesthe hollow parts around the light emitting devices. A modified examplewithout hollow part is produced for comparison with the light emittingapparatus including the hollow parts. In the modified example, in theaforementioned resin curing process, air bubbles are removed from resinso that the holding effect by the substrate side surfaces is reduced.Thus, the resin moves over the wiring substrate, and covers the lightemitting device surfaces. The resin is thermally cured so that acovering member without hollow parts is formed. Thus, the light emittingapparatus according to the modified example is produced.

The light emission property ΦY of both the light emitting apparatusesaccording to the two examples is about 0.37. The light flux of theexample with hollow parts is 206.4 Lm. The light flux of the examplewithout hollow parts is 203.2 Lm. Also, as for the ratio between lightfluxes before and after resin application/formation, in other words, asfor the ratio between the light flux of the light emitting apparatuswith the light transparent member adhered on the light emitting deviceon the substrate but without the covering member and the light flux ofthe light emitting apparatus according to each foregoing example withthe covering member obtained by forming resin on the light emittingapparatus without the covering member[light flux of apparatus withcovering member]/[light flux of apparatus without covering member], thelight flux ratio of the apparatus with hollow parts is 7.0%, and thelight flux ratio of the apparatus without hollow parts is 4.8%. Other ΦYvalues have similar tendency. That is, the apparatus with the hollowparts is higher in output improvement or power improvement.

A person skilled in the art predicts that restriction of light emissionarea by confining a part of the light emission area causes the followingdemerits, and therefore does not conduct such restriction. The reason isthat, since the number of reflection occurrences will increase, lightloss may occur, and as a result the emitted light flux may decrease.However, according to the present invention, contrary to thisconventional idea, since the light emitting apparatus has theaforementioned configuration, in other words, even when the lightemission area is restricted, it is possible to provide high luminancelight emission in that light flux reduction is suppressed andadditionally color unevenness is reduced. This effect is provided notonly by the light confinement effect by the sealing member but also by asynergistic effect by the plate-shaped light transparent member itselfthat can suppress uneven wavelength conversion amount distribution andcan effectively prevent color unevenness occurrence. In addition, in thecase where a plurality of light emitting devices are arranged under onelight transparent member having the wavelength conversion function, theluminance is high in proximity to a part right above each light emittingdevice, and the luminance decreases in accordance with a distance awayfrom the light emitting device. For this reason, luminance unevennessand color unevenness tend to occur in the light emission surface.However, according to the configuration of the present invention, suchluminance unevenness and color unevenness can be reduced. Therefore, itis possible to provide substantially uniform high luminance lightemission in the light emission surface. In addition, according to theproduction method in that the sealing member 26 is formed after thelight transparent member 15 is attached, it is possible to maintainintimate contact between the side surface side of the light transparentmember 15 and the sealing member 26 irrespective of the amount of thelight transparent member 15. Accordingly, it is possible to improvesealing environment for the light emitting devices enclosed by the lighttransparent member 15 and the sealing member 26. Therefore, it ispossible to provide a long-life light emitting apparatus. This effectcan be provided similarly by the case where space around the lightemitting device is filled with the sealing member, and the sealingmember covers the light emitting device surface as discussed in theexample 1.

EXAMPLE 3

Also, comparative evaluation is conducted for the difference of thermalresistance properties of members that composes the light transparentmember. The light emitting apparatus according to an example 3 issimilar to the light emitting apparatus according to the example 1. Thatis, the light transparent member 15 is formed of an inorganic material,specifically, a sintered member of YAG. On the other hand, in a lightemitting apparatus according to a comparative example 2, the lighttransparent member 15 contains an organic material, and is formed in aresin sheet of silicone resin mixed with YAG. The thickness of the resinsheet is about 100 to 150 μm, In the light emitting apparatusesaccording to the example 3 and the comparative example 2, except thatonly the materials of the light transparent members are different fromeach other from the aforementioned viewpoint, other members are the sameas those of the light emitting apparatus according to the example 1.

As for the light emitting apparatuses according to the example 3 and thecomparative example 2 that include the aforementioned light transparentmembers formed of YAG sintered material and resin sheet, respectively,to evaluate their thermal resistance properties, electric current of 700mA is applied to the light emitting apparatuses, and continuously emitlight for 1000 hours at environment of 85° C. FIG. 11 is a graph showingthe variation of the output as time elapses. Also, FIG. 12 is a graphshowing the variation of the chromaticity value (ΦY) as time elapses. Asshown in FIG. 11, in the light emitting apparatus according to theexample 3 that includes the YAG sintered material, the output tends toincrease as time elapses. After that, the output that has increased iskept. When 1000 hours have elapsed, the output increases 5% as comparedwith the start of measurement. On the other hand, in the light emittingapparatus according to the comparative example 2 that includes the resinsheet, the output greatly decreases at just beginning of measurement.After that, the output does not make a recovery. When 1000 hours haveelapsed, the output decreases 20% or more as compared with the start ofmeasurement.

Also, in the light emitting apparatus according to the example 3 thatincludes the YAG sintered material, as shown in FIG. 12, thechromaticity value (ΦY) slightly increases at just beginning ofmeasurement. However, the increase amount is small. In addition, even astime elapses, the variation of chromaticity value is small and stable.When 1000 hours have elapsed, the variation of chromaticity valueremains an increase of 0.003 as compared with the initial value. On theother hand, in the light emitting apparatus according to the comparativeexample 2 that includes the resin sheet, the chromaticity value (ΦY)greatly increases at jut beginning of measurement. After that, thechromaticity value decreases as time elapses. Although the variation ofchromaticity value is an increase of 0.01, the variation rate is largein a middle term, and the chromaticity is unstable.

FIG. 13 shows the state of the light emitting apparatuses according tothe example 3 and the comparative example 2 before the thermalresistance test. FIG. 14 shows the state of the light emitting apparatusof the comparative example 2 after 1000 hours has elapsed in the thermalresistance test under the aforementioned conditions. Both Figures areschematic plan view showing the periphery of the light transparentmember 15. As shown in FIG. 14, the resin sheet as the light transparentmember 15 according to the comparative example 2 is heavily damaged. Theheavy damage can be easily seen in that a part of the sheet is deformedinto a lump (deformed part 16 in the light transparent member). Also,the YAG phosphor mixed in the resin is greatly unevenly distributed. Inaddition, the cracks appear extending from the covering member 26 to thelight transparent member 15. On the other hand, in the light emittingapparatus according to the example 3, even after the thermal resistancetest, the shape of the light transparent member 15 formed of thesintered material shown in FIG. 13 does not change. Also, the YAGphosphor is unevenly distributed without uneven distribution. Thus, itcan be conceived that, even in the case where the resin sheet and thesintered material have the same covered form by the covering member 26,the heat dissipation properties and heat stresses of the lighttransparent members are different from each other. It can be evaluatedthat the YAG sintered material is superior to the resin sheet based onthe above result.

INDUSTRIAL APPLICABILITY

A light emitting apparatus and a method for producing the light emittingapparatus according to the present invention can be suitably applied toa light source for lighting, an LED display, a back light source, asignal light, an illuminated switch, various sensors, variousindicators, and the like.

EXPLANATION OF REFERENCE LETTERS OR NUMERALS

-   1, 20, 30, 40 . . . Light Emitting Apparatus-   2 . . . Light Reflective Material-   3A . . . First Electrode (N Type Pad Electrode)-   3B . . . Second Electrode (P Type Pad Electrode)-   5 . . . Growth Substrate (Sapphire Substrate)-   6 . . . First Nitride Semiconductor Layer (N-Type Semiconductor    Layer)-   7 . . . Second Nitride Semiconductor Layer (P-Type Semiconductor    Layer)-   8 . . . Light Emitting Layer (Active Layer)-   9 . . . Wiring Substrate (Sub-Mount)-   10 . . . Light Emitting Device-   11 . . . Semiconductor Structure-   13 . . . Transparent Conductive Layer (Transparent Electrode, ITO)-   14 . . . Protection Film-   15 . . . Light Transparent Member-   15 a . . . Light Emission Surface-   15 b . . . Light Receiving Surface-   15 c . . . Side Surface-   16 . . . Deformed Part of Light Transparent Member-   17 . . . Adhesion Material (Silicone Resin)-   24 . . . Electrically Conductive Member-   26, 26 b . . . Covering Member (Sealing Member, Resin)-   33 . . . End Surface-   100, 200 . . . Light Emitting Apparatus-   102 . . . LED Device-   103 . . . Case-   104 . . . Side Surface-   105A . . . Light Outgoing Surface-   110 . . . Phosphor Layer-   110A . . . Light Emission Surface-   111 . . . Coating Material-   111A . . . Light Reflective Particle-   L1, L2 . . . Light

The invention claimed is:
 1. A light emitting apparatus comprising: amount substrate; a first light emitting device mounted on the mountsubstrate; a light transparent member, wherein a lower surface of thelight transparent member is attached to an upper surface of the firstlight emitting device via an adhesive material, wherein the lighttransparent member has a plate shape and is positioned to receiveincident light emitted from the first light emitting device, and whereina first lateral surface of the light transparent member is locatedlaterally inward of a lateral surface of the first light emittingdevice; and a covering member that contains a light reflective materialand covers at least the lateral surface of the light transparent member.2. The light emitting apparatus of claim 1, further comprising: a secondlight emitting device mounted on the mount substrate; wherein a lowersurface of the light transparent member is attached to an upper surfaceof the second light emitting device via the adhesive material, andwherein the light transparent member is positioned to receive incidentlight emitted from the second light emitting device.
 3. The lightemitting apparatus of claim 2, wherein an outer periphery of theadhesive material on the first light emitting device is aligned with anouter periphery of the first light emitting device, and an outerperiphery of the adhesive material on the second light emitting deviceis aligned with an outer periphery of the second light emitting device.4. The light emitting apparatus of claim 3, wherein the covering membercontacts a portion of the lower surface of the light transparent memberthat is exposed from the adhesive material.
 5. The light emittingapparatus according to claim 2, wherein a second lateral surface of thelight transparent member is located laterally inward of a lateralsurface of the second light emitting device.
 6. The light emittingapparatus of claim 1, wherein the covering member contacts the lateralsurface of the light transparent member, the lateral surface of thefirst light emitting device, and a lateral surface of the adhesivematerial.
 7. The light emitting apparatus according to claim 1, whereinthe adhesive material is made of a silicone resin.
 8. The light emittingapparatus according to claim 1, wherein the light transparent member ismade of a resin, a glass, or a ceramic.
 9. The light emitting apparatusaccording to claim 1, wherein the light transparent member comprises aplurality of wavelength conversion members adapted to convert awavelength of at least a part of the light emitted from the first lightemitting device to a different wavelength.
 10. The light emittingapparatus according to claim 9, wherein the plurality of wavelengthconversion members are adapted to convert said at least a part of thelight emitted from the first light emitting device into light in yellowto red ranges.
 11. The light emitting apparatus according to claim 1,wherein an upper surface of the covering member is substantiallycoplanar with an upper surface of the light transparent member.
 12. Thelight emitting apparatus according to claim 11, wherein the uppersurface of the covering member and the upper surface of the lighttransparent member form an uppermost surface of the light emittingapparatus.
 13. The light emitting apparatus according to claim 1,wherein the first light emitting device is mounted on the mountsubstrate in a flip-chip manner.
 14. The light emitting apparatusaccording to claim 1, wherein the mount substrate is made of ceramic.